code: def main():
      """Small main program"""
      import sys, getopt
  
      usage = f"""usage: {sys.argv[0]} [-h|-d|-e|-u] [file|-]
          -h: print this help message and exit
          -d, -u: decode
          -e: encode (default)"""
      try:
          opts, args = getopt.getopt(sys.argv[1:], "hdeu")
      except getopt.error as msg:
          sys.stdout = sys.stderr
          print(msg)
          print(usage)
          sys.exit(2)
      func = encode
      for o, a in opts:
          if o == "-e":
              func = encode
          if o == "-d":
              func = decode
          if o == "-u":
              func = decode
          if o == "-h":
              print(usage)
              return
      if args and args[0] != "-":
          with open(args[0], "rb") as f:
              func(f, sys.stdout.buffer)
      else:
          func(sys.stdin.buffer, sys.stdout.buffer)
  
imports: import re
  import struct
  import binascii
label_desc: Use image node_id 26 for calling a global function with example usage: main() without return types